This invention relates to a method for embossing foamed polymeric sheet materials such as those employed in carpet backing, underlayment and the like.
The preparation of textured or embossed cellular or foam polymeric material and in particular of elastomeric foam materials has always presented some difficulty. Prior art approaches have included the application of embossing rolls to the foam sheet material under controlled temperature conditions to collapse the foam in predetermined areas, producing the desired pattern, and chemical methods in which the foaming agents or reactive crosslinking agents are applied in preselected areas on the surface of the polymeric material prior to foaming either to selectively foam the areas intended to be raised or alternatively to crosslink the areas intended to become depressed, unfoamed regions after the foaming step. The technique of collapsing the foam by means of embossing rolls requires careful control of the temperature and pressure conditions prevent a general collapse of the foamed material. Chemical methods are difficult to apply, often requiring added processing equipment to place the chemical agents in the desired areas accurately, and further steps are needed to ensure that a complete and stable foam structure results. Additionally, these methods have proved less than efficacious when applied to elastomeric foams and in particular to non-gel latex systems such as are commonly employed as backing for textile structures, as for example, in carpets and in foam rubber underlayment.
Accordingly, a method for embossing foam sheet material rapidly which would result in stable embossed patterns and which could readily be applied to the production of elastomeric foam-backed textiles, carpets and elastomeric foam sheet for underlayment and the like, is clearly needed.